1. Field of the Invention
The present invention relates to a cap of a vessel used to contain a liquid reagent in analytical instruments which are widely employed for chemistry, biology, and medical treatments and to a method for shielding reagents from the air. More particularly, it relates to a cap attached to the opening of the vessel for sealing it, which is opened only when the reagent is collected, thus allowing the contained reagent to be dispensed and shielding the reagent from the air to prevent the evaporation and the like of the reagent and to a method for shielding reagents by using the cap.
2. Description of the Related Art
Reagents for various analytical instruments used for chemical or biological analysis and determination are generally kept in glass or synthetic resin vessels. In order to prevent the evaporation and contamination of the liquid reagents contained in the vessels, the openings of the vessels are tightly sealed for supply, transportation, and storage. When they are used, in general, the reagent vessels are stored with the seal cap removed in insulating containers at a specified temperature which are provided to the various analytical instruments, and the reagents are automatically collected from the vessels with collecting probes attached to the analytical instruments.
Since the vessels in the insulating containers are opened in principle, the liquid reagents stored in the such vessels have many problems to be solved such as the risk of contamination, changes in concentration and composition with passage of time due to the evaporation of moisture and volatile components and the outflow of the reagents due to the tipping of the vessels in handling. Accordingly, various means have been proposed for preventing the contamination, evaporation, and deterioration of the reagents.
For example, Patent Document 1, Japanese Unexamined Patent Application Publication No. 5-294354 (claim 1, FIG. 1) proposes a “cap” which includes a top wall having an opening, a skirt without a screw which is made of a soft material, which is constructed to extend downward from the top wall, and slide on the vessel to come in tight engagement therewith, a slim arm having a sealing device for sealing the opening and moving between a sealing position and an unsealing position, and a biasing device for pushing the arm toward the sealing position.
Patent Document 2, Japanese Unexamined Patent Application Publication No. 11-194132 (claim 1), proposes a cap whose lid is capable of being turned laterally upward from a cap sealing position and having an inclined bistable hinge for opening a vessel and one or more catches capable of coming in contact with a device for pressurizing the cap.
Patent Document 3, Japanese Unexamined Patent Application Publication No. 2000-137032 (claim 1), proposes means for preventing the evaporation of a reagent by holding a liquid having a lower specific gravity than that of the reagent in a vessel, which is not mixed to the reagent, and by covering the surface of the reagent with the liquid.
Furthermore, commercially available analytical instruments use a vessel having an elastic thin sealing member serving as an inside plug at the opening, the sealing member having radial slits from the center, wherein when a reagent-collecting probe is moved downward, it is expanded downward and when the reagent-collecting probe is removed, it returns to a horizontal position by elasticity to cover the opening (Architect i2000, made of Abbott Laboratories).
However, the “cap” which has the mechanically openable and closable section as described in Patent Document 1 has a very complicated structure and so requires a device for pressurizing the “cap” which is set to the vessel when applied to various analytical instruments, thus having problems to be solved in practice such as requiring an additional function and production cost for the vessel.
As described in Patent Document 3, the means for preventing the evaporation of a liquid reagent by covering the surface with a liquid having a lower specific gravity than that of the reagent has not the mechanical structure as in the above-described “cap”, offering advantages of no contact between the reagent and air and preventing evaporation. However, since the opening is always opened, the leakage of the reagent due to tipping of the vessel in handling cannot be prevented.
Furthermore, the commercial inside-plug type requires careful operation in the process of attachment of the plug after the removal of the cap so that the reagent is not contaminated and particularly has the problem of contamination of a collecting probe and also of the reagent due to contact of the reagent-collecting probe with the sealing member.